


The blue tailed merman.

by ohmerthurcharm



Category: Merlin (TV)
Genre: Arthur wants it, Begging, Grieving Arthur, Gwaine is a tentacle monster, Gwaine makes Arthur pass out, Human!Arthur, I guess it's a threesome technically, I'm Serious, Insult Kink, Lots of Cum, M/M, Magic, Making Out, Merlin and Arthur are inloooooove, Monster Dick, Multiple Orgasms, Orgasm Delay/Denial, Overstimulation, Porn, Porn With Plot, Porn with Feelings, Pornalot_2018, Praise Kink, Sea Monsters, Sex Magic, Size Kink, Tentacle Monsters, Tentacle Sex, Trust, Turned human Merlin, but Merlin and Gwaine don't have sex, but Merlin watches and helps a little?, consort!merlin, intense pleasure, inverted sex hole, king!arthur, knots, massive dick, merman!Merlin, name calling kink, overwhelmed Arthur, slut!arthur, the little mermaid disney plot, thick liquid goop as lube
Language: English
Status: Completed
Published: 2018-10-11
Updated: 2018-10-11
Packaged: 2019-07-29 11:21:24
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 4,084
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16263164
Author URL: https://archiveofourown.org/users/ohmerthurcharm/pseuds/ohmerthurcharm
Summary: The little mermaid with a twist.Prince Arthur is now taking charge at being King. his father King Uther, after suffering the loss of his daughter Morgana is weakening in strength and spirit. His uncle has helped him with the difficulties of being King but sometimes he wishes to be alone. Ever since he was saved by that merman, he's been hoping to see him again, he might not know what the creature looks like but he knows, deep down that the merman is there, somewhere. What Arthur doesn't know is how his uncle fits into all this.





	The blue tailed merman.

**Author's Note:**

> I'm so happy that i get to partake in this awesome Challenge. This is Challenge number one: Disney.  
> I hope you all enjoy :) Have a good day.

Arthur sneaked out of the sleeping castle in the middle of the night and breathed in the cold air, the smell of the ocean was strong. He sighed happily and stared at the star filled sky. Ever since his father became ill from his sisters betrayal, he’s been burdened by Kingly duties as his father wasted away in his stuffy chambers. It felt good to be outside, where the ocean’s rumble was the only thing filling his ears. 

He made his way down the grand steps that lead to the ocean’s shore, there he watched as the ocean lapped at the edges. The last steps were covered in algae. He carefully stepped out of his boots, stuffing his socks into them before stepping down until he sat on the last step, his legs submerged in the ocean. It was cold but Arthur welcomed it happily. Enjoying the feeling as it moved against him.

He hummed happily and closed his eyes, leaning his head back as he heard the bigger waves in the distance crashing against the cliff side. 

Arthur loved the sound, the hissing, the bubbling, and the whoosh of the gentle night’s wind. It was music to his ears. The pull and push of the water calmed his nerves. He didn’t care that his pants were soaked.

Arthur smiled to himself and shook his head slightly. Nothing could beat this. 

He felt so peaceful, so serene. He remembered being scared of this area when he was little, being alone in a dark place terrified him but over the years he conquered his fear and it became his favorite place in the castle. 

Just then he felt something brush up against his leg and he opened his eyes and looked down. There were bubbled appearing and he felt something grab his leg but not tightly, something…a thumb rubbed against his ankle.

He blinked and his eyes widened when he saw a head emerge from the water before a face stared back at him. It was as almost as pale as the moon; his skin was wet and sparkled slightly. 

Arthur gulped and licked his lips and felt his mouth become dry. The figure was handsome, his cheekbones were prominent and sharp, his eyes were like blue crystals, gleaming and sparkling. His hair was as black as the night sky. His lips were plump and touched with the color of a pink rose. They were so kissable. 

Arthur leant forwards unknowingly and the figure moved up, his hand reaching out and cupped Arthur’s cheek, it was cold to the touch. His thumb rubbed against his cheekbone, a curious look graced his face. 

“Uh…..who….are you?” Arthur asked softly. 

The figure smiled at him gently, his eyes creasing slightly. 

Arthur blinked slowly. 

The face looked pained then before he moved further up and pressed his cold lips to Arthur and pecked him gently. 

Arthur let out a softly breath and closed his eyes, he returned the kiss gently, cupping the man’s nape as he deepened it and felt the man’s lips grow warm. 

He moved his tongue against the man’s bottom lip before it slipped into his opened mouth and explored, it was warm and welcoming. Arthur gulped and deepened the kiss, he heard the man moan softly, his hand now on Arthur’s nape and away from his cheek, fondling Arthur’s hair. 

Arthur moaned, feeling lust take control and kissed deeper, taking more control over the kiss. The man melted and shuddered, letting out soft and desperate sounds. Arthur’s member hardened and they broke off, panting. 

That was when he saw the tail, the fish tail…..the merman’s tail. 

It was shimmering under the moonlight; different shades of blue graced the scales. 

Arthur looked into the merman’s eyes then. 

They were pleading.

Arthur felt the merman’s hands hold onto his arms, gently pulling him closer to the water, Arthur leaned forwards as he stepped into the ocean; he was now submerged until his chest. 

The merman looked at him before swimming closer and pressed his chest against Arthur’s, faces inches away from one another. 

Arthur felt his hands sneak under his tunic, sliding up his chest and rubbed there gently, staring at him with need and want. 

Arthur offered him a smile before capturing his lips, the merman eagerly kissed back, desperate. 

Arthur tore off his tunic and grabbed the merman’s arms and kissed him roughly before his hands traveled lower till he felt the slimy tail and he felt his hand being guided to his front and felt a dip before his finger slid in somewhere, it’s walls were soft and warm to the touch, suddenly the man broke off the kiss and threw his head back, moaning. 

Arthur panted and looked down to just make out a hole in his tail, bellow his bellybutton. 

Arthur rested his hands on the creatures’ hips and stared at him, the creature was looking at him again, gasping and mouthed something but no words, no sound came out. 

‘Please.’ Was what he could read from his lips. 

Arthur nodded and let out a soft whimper, as his member was stiff against his fabric, when he tugged off his pants and underwear his member bobbed out, free and hard. 

The creature looked down at it, blinking in surprise. It was red and angry; already pearls of pre-cum were forming at the tip. 

Arthur gasped as the merman’s finger swiped off a bit of his cum before moving it to his lips and sucked on it, licking his finger and hummed happily. 

Arthur stared at him, dumbfounded. 

The creature opened his eyes and looked at him, his eyes hooded and smiled lightly.

Arthur nodded, dazed and grabbed the creatures hips and slowly slipped his member into the hole as it went in he gasped at the sensation, it grew tighter the more he went in and stopped. 

The merman whined, wrapping his arms around Arthur’s strong shoulders. 

Arthur slowly moved back before thrusting in again, earning a cry from them both. 

Arthur moved slowly, gasping and moaning. The creature clawed at his back, letting out lewd noises that echoed. 

“Ahh…ahhh…ahh…ahh…ahhngg!!” The creature moaned as Arthur moved inside him. 

Arthur panted, groaning. “Fuck your good! Nugh!!”

The creature gasped, drooling. “Ahh!!!!”

Arthur groaned loudly, the noises of skin slapping against skin was too much for him, he was surprised at how loud he was. He didn’t know he could make such sounds. 

He cried out as the merman’s nails clawed his back more, he arched his back, enjoying the feeling and hissed. 

The tail wrapped around him loosely and Arthur pounded into him harder, feeling himself going much deeper. The feeling was glorious; he was seeing stars through his closed eyes. 

Of all the maids and manservants he’s tupped, nothing could compare to this.   
The creature’s walls were slick now and hot, it was pulsing almost, the deeper he went, the more pleasure he felt. There were small nubs at the ends of the walls, thousands of them, some bigger than the other, it massaged his member, coaxing it into hardness, he felt it letting out some sort of liquid, it was sticky but smooth and it made everything slippery. 

Arthur’s eyes rolled back as he felt close, he cried out and the creature tightened around him. Suddenly his whole body shook and he held onto the creature so he wouldn’t fall and then he slammed into him, hard before spending his seeds deep inside. He moaned loudly when the nubs swelled, trapping his member deep inside him, their hips connected. 

Arthur shouted loudly in pleasure when he felt the nubs sucking every inch of his member, Arthur whimpered and moaned, squirming and thrusting as the creature moaned loudly, sobbing in pleasure, clinging onto him for dear life. 

Slowly the walls opened and Arthur slipped out, a trail of a see-through lubricant attached itself to the tip of his member before weakening and melted away. 

Arthur gasped; coming down from the high and the creature slowly let go of him before smiling at Arthur happily. 

Arthur smiled back and leaned in, kissing him deeply. 

“Arthur! Is that you!?” A familiar voice called.

Arthur pulled the creature close, crouching low as he stared at a pair of boots appearing before his uncle showed himself on the steps. 

“There you are, I was worried. Is every….oh…” He said, noticing the creature. 

Arthur blinked and gulped. “I’m busy…uncle…”

“I see…” He said and Arthur saw as his uncle rubbed his necklace that was tucked under his tunic. Arthur was always curious about it when his uncle started wearing it. 

He suddenly felt the creature tremble under his hold. Arthur looked back to see the merman staring at his uncle in fear. 

“Uncle?” Arthur asked before looking at him to see him clutching the necklace tightly, glaring at the creature. 

“You! I told you never to return here!” He shouted. 

Arthur glared at him. “Did you hurt him in anyway, uncle? Show me the necklace.”

His uncle suddenly looked furious and Arthur grabbed a rock and threw it at his uncle’s feet. His uncle snarled angrily before slipping and fell onto the last step hard before slipping into the ocean. 

There was a sudden glow of light before he saw the creature gasping, glowing. 

The glow then subsided and he stared at Arthur in awe. 

“Arthur!” He breathed, grinning. 

The man blinked. “You can…talk.”

“I wanted to meet you for so long…I asked your uncle if I could see you and he said if I gave him my voice I could…but it was a trap and when I gave it to him, he banished me…he was holding my power against me…” He said. 

Arthur frowned, angry. “How dare he.”

The merman looked at him then. “It’s ok….he’s dead now. Do you…. remember when your ship caught alight and you fell unconscious as it sunk?” 

Arthur could only nod.

“I saved you…” He said, grinning through the tears. 

“You…..you were him weren’t you!?” Arthur said and grinned, holding onto Merlin. “You were the merman I’ve been looking for all this time!”

The merman nodded, grinning. 

“Tell me your name, please.” He pleaded with glee. 

The merman giggled happily. “It’s Merlin.”

“Merlin.” Arthur breathed in delight. “Merlin, thank you for saving my life.”

“-And thank you for saving mine.” Merlin grinned happily. 

They shared a kiss. 

“Go on…before you catch your death.” Merlin smiled and Arthur sighed. 

“You’ll…be here tomorrow night?” Arthur asked hopefully.

“If you’ll have me….I’d like to be with you forever, Arthur.” He said, shy. 

Arthur looked at him happily. “I could wish for nothing more.”

The next week, his Father was assassinated by Odin and Arthur was crowned King. 

He went down the steps in his underwear in the dead of night, his cheeks were hot as tears streamed down them, and he almost slipped before he got into the water. 

“Merlin!” He choked out before covering his face and wept. 

He felt hands on his wrists and felt them being moved down before he saw Merlin there, worried and loving.

“Arthur….” He said softly. 

Arthur grabbed him then, kissing him deeply before pressing his back against the castle wall and tore off his underwear and held Merlin tightly, their naked bodies pressed against each other. 

Merlin held onto him, feeling Arthur’s body heaving as he wept against Merlin’s neck. 

“Shhh shhh…” He hushed, stroking Arthur’s hair. 

“He’s gone.” Arthur gasped out.

“Yes….but he’s in a better place now…probably happier.” Merlin hushed. 

Arthur nodded slowly and Merlin’s hand moved down slowly, rubbing Arthur’s ass cheek gently, lightly squeezing it and the man’s eyes fluttered closed.

“Let me please you…” Merlin hushed and licked Arthur’s neck, sucking on a spot that made the King’s knees weak. 

“Nugh….fuck….i…” He breathed out. “I can’t….my legs.”

Merlin noticed a bolder and wrapped his arms around Arthur before swimming them there. He draped Arthur over it before hoisting himself on top of him. 

Merlin leaned down and captured Arthur’s lips happily. 

Arthur moaned and kissed back, holding onto Merlin as he made out with him. 

Eventually Merlin moved back and noticed Arthur’s member poking his tail. He slowly moved down against it and gasped. Arthur grit his teeth, groaning as Merlin’s hole took in Arthur’s erect member. 

“Ahhh!! Fuck…yes…oh gods yes!” Merlin cried out and used his arms to balance himself as he moved up and down as Arthur grabbed his hips, moving Merlin back and forth with ease. 

“Fuck, Merlin. You’re too fucking good, oh gods!” He cried out and shifted his legs as pleasure consumed him. 

Merlin moved happily, his head bobbing slightly with the movements. 

“Ahhh….Mmmmph…” The merman bit his lip, shuddering. “Ohhhhh!!”

Arthur let out a throaty groan as he dug his nails into Merlin’s hips, earning a hiss from the merman. 

“More, more…please I need more, Merlin!” He cried out and the merman looked at him, panting. 

“You….you aren’t satisfied yet?” He gasped out. 

Arthur nodded. “I am….gods I love this but…fuck…I need more…I’m a-” He panted out but Merlin interrupted him. 

“Greedy whore?” He asked and Arthur gasped, his cheeks flushed more. 

“Yes…” He breathed out. “Yes I’m a greedy whore who needs more…more….so much more from you!” He cried out. 

Merlin smirked then, his pupils turning into slits before he chuckled. “Alright….i never knew the King of Camelot was such a desperate slut….” He said and leaned in, whispering against his ear. “I’m going to fuck you so good but this is a two man job.”

Arthur moaned, his eyes closing. 

“You just lie back…. make yourself comfortable…” He soothed out before moving further up. 

Arthur opened his eyes to see Merlin watching him with a hint of concern. 

“Can I use my powers on you?” He asked. 

Arthur nodded. “I trust you…”

Merlin smiled then. “I trust you too….alright…” He said and took a breath before his eyes turned a brilliant gold colour, it was glowing beautifully, lighting up the skin around his eyes beautifully. 

Arthur stared at him, his body relaxed completely then, his arms moved down from the man’s hips and onto the rock bellow him. 

Merlin moved happily, staring at the man as he moved before slipping out and Arthur let out a soft whine. 

Merlin whispered a spell and Arthur saw a glittering, golden thread appear from nothing and wrapped around his body and Arthur felt nothing and then it glowed and Arthur moaned deeply at the sensation, his scenes were being toyed with. 

He could feel his member weeping, hard as rock and in need of attention. His pleasure was consuming him, body and soul. 

Arthur writhed bellow him, moaning and panting. 

“Merlin!” He cried out. “Merlin yes!! Fuck, MORE!” He cried out desperately and began to sob as he bucked his hips up with no avail.

Merlin smirked and moved his hand so they were fondling Arthur’s balls. The King shouted in pleasure. 

“Fuck, Fuck why can’t I cum!?” He shouted. 

“I won’t let you…not yet…” Merlin purred out. 

Arthur groaned, gasping. “Merlin….Merlin please.” He begged desperately. 

“Oh…I love how you beg my name, King.” He said softly, brushing off the damp hair from Arthur’s forehead and placed a kiss there. “Look into my eyes, Arthur.”

Arthur panted and looked at him and Merlin’s eyes once again turned golden and the man’s eyes rolled back into his head, his back arching and let out a cry. Arthur wept brokenly and gasped when he felt something wet on his leg and saw a tentacle there.

“Don’t worry…he’s a friend, he’ll make you feel good.” Merlin hushed, petting his hair. 

The tentacles moved further up, wrapping around Arthur’s legs, there were smaller tentacles that wrapped around his member, he felt suctions on the side of it, sucking on his member happily, slowly coiling and uncoiling around it, pulsing slowly. 

Arthur moaned happily, watching in a daze as they came further up. 

Arthur gasped as his legs were lifted up and spread apart and the creature emerged, the top part was of a human looking man, he had luscious brown hair and wore a necklace. The bottom half, bellow his hip were great big tentacles. 

Merlin sat behind Arthur’s head and moved his shoulders up, Arthur’s head resting against Merlin’s chest as he watched the tentacles wrap around his chest and arms. He felt his wrists being moved back and tied behind his back.

“Yes…yes oh gods yes!” Arthur cried out. 

The creature came closer and he saw the tentacles curl around him more, consuming his body as he saw a large member under the tentacles. About four large tentacles moved to the side and up, exposing the throbbing monster of a cock. On closer exception it was a tentacle itself but shorter. 

Arthur felt Merlin’s spell lesson and he let out a cry as his cum shot out and he slumped back, gasping, letting out happy noises and shifted. 

The creature smirked at him. “You found a good one here….”

“I have, haven’t i? Make sure you give him a good fuck, Gwaine.” Merlin said happily. 

“My pleasure, Sire.” He said, resting his hand on his chest almost mockingly but the tone was friendly. 

Arthur stared. “Please…need….my hole filled. I want you to fuck me.”

“As you wish.” Gwaine said and moved closer before Arthur watched as another tentacle, that was dripping with a thick liquid prodded his hole and slowly eased in and Arthur cried out. 

“Yes…YES!” Arthur screamed, squirming as the tentacle moved inside him, opening him up, lazily moving back and forth, the liquid was warm as it spilled out and down Arthur’s thighs and back. The noises made his member weep with pre-cum.

“Mmmph….” Arthur moaned and whimpered, fucking himself against it. 

“You’re a hungry one you are….” Gwaine purred.

Arthur could only nod and cried out, his eyes closing as he felt the tentacle almost double in size inside him, it was going deeper and deeper inside of him and Arthur trembles, gasping and moved his hand against his belly and he could feel it, the tentacle prodding. 

He began to weep. “More!!”

“More what?” Gwaine asked. 

“I want your cock…your big, fat cock inside me!” He cried out and Gwaine chuckled. 

Just then the tentacle slipped out, it must have been magic because Arthur’s hole was opened up perfectly for that monster of a cock. 

He saw the tentacle move closer and Arthur gasped.

It was red and had thick, pulsing veins along it, it…it had a knot. 

Arthur gasped as the head pressed against his hole. 

“Good…good, Arthur…just breathe now…” Merlin hushed, petting his hair. 

Arthur nodded and breathed deeply and shouted when it began to move against the hole, it was more solid, something huge and round was forcing it’s way in.

Arthur came again.

The creature, Gwaine was looming over him now, watching him curiously as the member slowly went deeper in, Arthur’s hole was red and puffy, stretching to an unimaginable size and suddenly there was a pop sound and Arthur screamed in delight as the ball shaped thing was now inside of him, stretching him and adding pleasure beautifully inside him. 

“Ah…my knot is in now….your a good little slut huh?” Gwaine panted and fiddled with Arthur’s nipple, massaging his breast with the palm of his head slowly. 

Arthur could only focus on his breathing as the member, the massive thing started to sink into his hole, Arthur watched in awe. 

“Good cumslut….” Gwaine praised him, teasing the nipple back into hardness. 

Arthur moaned as the member entered him fully and he squirmed, crying. 

Arthur gasped and looked down to see an indent in his belly, he rubbed against it, feeling a hard thing inside him. 

“That’s my cock…it’s buried deep inside you.” Gwaine hushed against Arthur’s ear and licked the shell of it before sucking on his earlobe. 

Arthur closed his eyes, moaning and his body jerked now and again at the sensation. 

“M…M…Merlin.” He moaned out and he felt a kiss on his head. 

“My dear Arthur?” A loving voice answered. 

Arthur couldn’t help but thrust his hips against the member; he knew Gwaine was being good to him as his fat cock wasn’t moving. He was giving Arthur time to adjust to it, but he couldn’t stop himself from moving.

“I…..I feel so good.” He moaned. 

“As do i….” Merlin panted out. “You look so good, Arthur…like this….”

Arthur moaned and fucked himself against the member; his whole body was aching in heat.

“You’re my good slut aren’t you?” Merlin asked fondly and Arthur nodded. 

“I’m your slut…. your whore.” Arthur breathed out and sobbed. 

Gwaine took that as an invitation for him to move and he bucked into Arthur happily. 

Arthur screamed happily, he felt himself cumming again. 

Merlin leaned down and captured his lips, their tongues mingled together as Arthur’s body tensed and relaxed as Gwaine pounded into him. The tentacle creature was groaning happily above them.

Arthur tugged at the tentacles but they didn’t budge and he moaned happily.

Merlin broke off the kiss and looked at Arthur. “Watch Gwaine.”

Arthur looked at the creature and saw Gwaine was lost in pleasure, pumping into him happily. 

Arthur panted and groaned, feeling close. “Need to cum!” He gasped out, trembling. 

“Then cum, my darling.” Merlin said.

Arthur cried out and came before gasping heavily, moaning nonsense. 

Gwaine then let out a wail before cumming deep inside him and slipped out with a pop. 

Arthur moaned happily and stared at the creature. “Thank you.”

He winked at him. “My pleasure, princess. You were a true delight.”

“As were you.” Arthur mumbled and felt the tentacles move away, except one, it was smaller with a round, knot like shape at the end. It prodded Arthur’s lips and he opened his mouth and it slipped in and Arthur moaned, sucking on it happily. He tasted something and a liquid jetted out of the tentacle, the knot disappearing and he sucked on it happily, moaning and gulped the liquid down. 

He felt the tentacle grow larger and he licked around it, his eyes closed and sucked happily as it explored his mouth. 

Arthur moved his hand to his hardening member and touched himself happily, jerking himself off before he felt heavy and slumped against Merlin, the tentacle left him and Arthur breathed slowly, curling up. Fast asleep.

Merlin looked up at him. “Thank you, Gwaine.”

“Anytime.” He said. “You sure have a keeper.” 

Merlin grinned and looked down at his sleeping King. “I do…”

“I’ll see you at home…whenever you choose to come back…but if you don’t…I wish you luck…” Gwaine said. “Don’t hesitate to call me if you need me…for sex or otherwise.”

“You’re a true friend, Gwaine.” Merlin smiled and the man disappeared into the sea. 

Merlin looked down at Arthur who slept peacefully, his soft member resting against his thigh. 

Merlin took away the spell on Arthur and took a deep breath and cried out in pain as his tail separated, morphing into human legs. 

Arthur shifted slightly against it and Merlin looked down to find himself human.

With great care Merlin lifted Arthur into his arms and slipped into the water and went to the shore before slowly going up the stairs and into the palace, he was alone as everyone was asleep and made his way through the castle, confused and Arthur woke slowly. 

“Huh?” He asked and looked up and gasped. “Merlin.” He whispered. 

Merlin smiled at him. “Were is your chambers?”

Arthur guided him and Merlin cleaned him up before tucking him into bed and slipped in beside him before resting his head on the pillow. 

“Night….Merlin…thank you for tonight…and….and for carrying me here…did you shift?” He asked and Merlin nodded. 

“Yes…when I was broken away from the curse and when I got your seed in me, I had the power to change my shape.” Merlin smiled. 

Arthur pulled the man close and nuzzled against his chest before sleeping.

The next day Merlin was made Arthur’s consort and they lived happily ever after.


End file.
